Land Detector Configuration

The land detector is a dynamic vehicle model representing key vehicle states such as landed and ground contact.

Configuring Auto-Disarming

By default the land detector does detect landing, but does not auto-disarm. If the hysteresis parameter COM_DISARM_LAND is set to a non-zero value the system will auto-disarm after N seconds (the value it is set to).

Multicopter Land Detector Configuration

The complete set of parameters is available in the QGroundControl parameter editor under the LNDMC prefix. The key parameters that might differ per airframe are these:

• LNDMC_MAN_DWNTHR - the threshold (in percent, default is 15%) for how much manual throttle is allowed to be considering the state as landed. Systems with very high thrust-to-weight ratios like racers might need a lower setting here (e.g. 8%).
• MPC_THR_HOVER - the hover throttle of the system (in percent, default is 50%). It is important to set this correctly as it does not only make the altitude control more accurate, but also ensures correct land detection. A racer or a big camera drone without payload mounted might need a much lower setting (e.g. 35%).
• MPC_THR_MIN - the overall minimum throttle of the system. This should be set to enable a controlled descend.
• LNDMC_THR_RANGE - this is a scaling factor to define the range between min and hover throttle that gets accepted as landed. Example: If the minimum throttle is 0.1, the hover throttle is 0.5 and the range is 0.2 (20%), then the highest throttle value that counts as landed is the min throttle plus (0.5 - 0.1) * 0.2 = 0.08, so a total throttle of 0.18.
• LNDMC_POS_UPTHR - throttle level to trigger takeoff (in percent, default is 65%). If the pilot raises above this threshold the system will attempt to take off. This value should be greater than the hover throttle.

Fixed Wing Land Detector Configuration

The complete set of parameters is available under the LNDFW prefix. These two user parameters are sometimes worth tuning:

• LNDFW_AIRSPD_MAX - the maximum airspeed allowed for the system still to be considered landed. The default of 8 m/s is a reliable tradeoff between airspeed sensing accuracy and triggering fast enough. Better airspeed sensors should allow lower values of this parameter.
• LNDFW_VELI_MAX - the maximum velocity for the system to be still considered landed. This parameter can be adjusted to ensure a sooner or later land detection on throwing the airframe for hand-launches.